The long-term goal of our research is to discover the details of the biochemistry of virus phi X174 DNA replication. We will examine the roles of host cell proteins in the catalysis and control of this replication. Virus DNA synthesis will be examined in mutant host cells defective in DNA synthesis genes. Virus DNA replication will also be examined in protein extracts of host cells to determine what proteins are required for catalysis and control, their mechanisms of action, and the structures of the DNA intermediates and products.